The present invention generally relates to a communication device and, more particularly, to a mobile communication device having an internal monopole antenna integrated with a conductive surface.
One of the components that seem to have been given less consideration at the mobile level by phone manufacturers is the antenna. In fact, little change has been done at the antenna. With the progress in semiconductor manufacturing processes and telecommunications techniques, however, interest in a compact, light-weight and low-profile antenna for mobile devices is growing
A variety of low-profile monopole antennas that are designed to be embedded inside the casings of mobile devices, such as mobile phones and personal digital assistants (“PDAs”), as internal antennas have been demonstrated recently. However, during conventional antenna design processes, an internal monopole antenna is usually tested in a stand-alone condition without taking into consideration other components such as the shielding metal case of an RF (“radio frequency”) module, RF circuitry and the battery, which are disposed near the internal monopole antenna. Failure to integrate the antenna and shielding metal case may generally result in an uneconomical use of the space within a mobile communication device, and may in turn contradict the goal of being compact and low profile.
FIG. 1 is a schematic diagram of a conventional mobile device 10. Referring to FIG. 1, the mobile device 10 includes a ground plane 11, a shielding metal case 12, an antenna 13, a shorting pin 14 and a feeding pin 15. The antenna 13, in the form of a printed inverted-F antenna (“PIFA”), is separated from the shielding metal case 12 by an isolation distance d, which is required to avoid coupling effects between the antenna 13 and the shielding metal case 12 or associated nearby components. Such an isolation distance d may generally be about 7 mm (millimeter) or greater so that the performance of the antenna 13 is not degraded by the coupling effects. The requirement for such an isolation distance d limits the effective usage of the internal spacing in a mobile device.
It is therefore desirable to have a mobile device that has a relatively small distance between an internal monopole antenna and a shielding metal case or other nearby components of the mobile device without compromising the performance of the monopole antenna.